EFFECTS OF IMPAIRED INSULIN-SECRETION ON THE FERTILIZATION OF MOUSE OOCYTES

We have studied the effect of moderately impaired maternal insulin sec retion on oocyte chromosomal constitution, fertilization and zygote DN A synthesis, Female mice were injected with a single dose of streptozo tocin (65 mg/kg) 14 days before fertilization/ovulation. Zygotes/oocyt es were recovered from control and subdiabetic mice on day 1 of pregna ncy, Compared with control animals, subdiabetic females showed a signi ficant difference in the proportion of zygotes/oocytes. The subdiabeti c mothers had a lower percentage of zygotes and a higher percentage of unfertilized and degenerated oocytes in comparison with control anima ls, The investigation of [H-3]thymidine incorporation did not show any influence of the maternal subdiabetes on the initial zygote DNA synth esis, An analysis of the ovulated oocytes at the metaphase II stage is olated from subdiabetic mice did not reveal increased chromosomal anom alies in comparison with the controls, Control and subdiabetic mothers had a similar percentage of oocytes with a normal haploid set of chro mosomes, and the incidence of aneuploidy/diploidy did not differ signi ficantly, These observations suggest that insulin changes in subdiabet ic mothers had a deleterious influence on oocyte fertilization in mice , but apparently they did not have any effect on the nuclear events.